Gas separation apparatus with liquid level controller



Nov. 4, 1952 551-1055 2,616,514

GAS SEPARATION APPARATUS WITH LIQUID LEVEL CONTROLLER Fi1 ed Sept. 20,194s HOlVHVdBS I o aanssiad MO I N l :5 .J g b E E 'm 85 k a L) {T P0 R6*} N 4 no I (\l I l INVENTOR.

HENRY E.SHOBE BY Z A TTORNE YS controller having no packing glands;

exposed to the high pressures.

Patented Nov. 4, 1952 UNITED STATES TENT OFFICE GAS SEPARATION APPARATUSWITH LIQUID LEVEL CONTROLLER Henry E. Shobe, Bartlesville, Okla,assignor to Phillips Petroleum Company, a corporation of Delaware 8Claims.

1. This. invention relates to liquid level controllers- In one of' itsmore specific aspects it relates to liquid level controllersfor use ingasliquidv separator tanks and has special utility in separatorassemblies operating under high pressures.

Conventional liquid level controllers are usually dependent on a floator on the difference in weight of a column of liquid and the gas incontact with it. In the float type of controller, the float may be ahollow objector a solid, but in either case it is sufiiciently lighterthan an equal volume of liquid to actuate a valve or to actuate a pilotwhichrelays the desired motion to an air or electrically actuated motorvalve. may be contained in the separator vessel itself or in a specialcase having lines connecting the case with the liquid and the gasportions of the separator. The float is usually attached to a lever armwhich in turn is fastened to a shaft which transmits motion of the floatto points outside the separator vessel or the float case. In eithercase, a packinggland is necessary to prevent leakage of gas or liquidaround the shaft.

The second class of controllers uses the Weight of'a column of liquid tooperate some type of pilot or switch which in turn relays the desiredmotion to a motor valve.

An object of my invention is to' providea liquid level controller foruse inliquid gas separators.

Another object of my invention is to provide a liquid level controllerforuse'in' liquid gas separators operating under high pressures; Anotherobject of my invention is to provide a liquid level Another object of.my invention is to provide a; liquid level controller for use in highpressure liquid-gas separation having a minimum of'mo'ving parts Stillanother object ofmy'invention is to provide a liquid level controllerapparatus which is simple and inexpensive to construct and'which may berepaired or" replaced with a minimum of expense. Still otherobjects andadvantages of my invention will be obvious to thoseskilled in the artupon reading the" following disclosure taken in conjunction with theattached drawing, the disclosure and drawingforming a part of thisspecification.

In thedrawing, Figure 1 represents diagrammatically one form ofapparatus in which the process of my invention may be carried out.Figure 2 represents diagrammatically the construction of one form ofstand pipe used in conjunction with the apparatus of Figure 1. Figure 3represents another embodiment of standpipe apparatus.

The float Referring now to Figure 1 a separator tank. [2 is equippedwith three pipe connectionsone at a midpoint for passage of" gas andliquid-feed stock into the tank- 12.3, connection'at the top of the tankis a gasoutlet pipe l3,, while-the connection in the lower portion ofthe tank is for withdrawal of separated liquid. Pipe I5 is connectedwith a motor valve I B, which in turn is connected with a pipe 11. Pipel1 leads-to a second separator vessel [8. This latter vessel contains anoverhead outlet line and a lower liquid outlet line [9. A conventionalliquid level controller 29 is shown for controlling How of liquidthrough the line 19. The overhead pipe 20 contains an orifice 21 andmaterial flowing through this pipe and orifice passes on through a pipe26'. A flow controller apparatus 24' has a pipe connection 22 to pipe20upstreamof the orifice 2| and a pipe 23" connecting with pipe-26downstreamof the orifice. In case the flow controller apparatus 24operates pneumatically then air or other gas may come from a. source,not shown, through a line 21, while if'this controller operateselectrically, line 2Tmay represent wires connected to a source of'electricity, also not shown. A pipe or wires 25 connects the flowcontroller 24 with the motor of the motor valve 16.

Figure 2 represents diagrammatically a stand pipe apparatus for use inthe loweror liquid containing portion of a high'press'ure separatorvessel. See reference numeral 14, Figure 1. This stand pipe I4 may beco'mposedofi an elongated tube 3! of small diameter havingboth endsopen. Surrounding this small diameter tube is-a tube 32 having aconsiderably larger diameter. The upper ends of' tubes 32- and 31 arejoinedtogether in' an'ymanner d'esired'so as to produce a gas-tightconnection. To the other endof the outer tube 32 is connecteda venturior other type of constriction 34 so constructed that the lower end 35 ofthe inner tube 3! terminates at approximately the neck of the venturi.In the sidewall of the larger diameter tube 32 is an opening 31. Thisopening may be merely an open space in the cylindrical wall of the tubeor it may be a short horizontally disposed tube as shown in the drawing.The lower end of the venturi 34 may be connected with a pipe'36 for thepassage of materials through the'sid'ewall of the separator I2 andthrough pipe l5. However, if desired, the tube 36 may be a straight tubefor passage through the bottom of the separator !2. However, it may bepreferable to construct this tube as illustrated in Figure 2 so thatthis tube may pass through the sidewall of thetank;

In the operation of this" liquid level controller,

gas and liquid to be separated may be introduced through the feed line II into the separator tank I2 at about a midpoint. In this separator thegas rises and passes out through the overhead gas line I3 and the liquiddrops to the lower part and when the level of the liquid reaches opening31 (Figure 2) it enters the stand pipe I 4 and flows through line I5,the motor valve I6 and through line I! into a second separator vesselI8. This separator vessel I8 operates at a lower pressure than theseparator vessel I2. In the separator I8 liquid drops to the bottom andpasses through the liquid outlet line I9 as controlled by the liquidlevel controller apparatus 29. Gas flashed and separated from the liquidas the pressure is reduced in valve I 6 rises to the top of theseparator I8 and passes through the line 20, orifice 2I and line 26 tosuch disposal as desired. If a back pressure regulator is not used inline 20, the low pressure separator I 8 may then operate atsubstantially atmospheric pressure or at such back pressure as may beexerted in line 26 from some extraneous source. If it is desired tooperate the separator I8 at some pressure a back pressure regulator maythen be installed in the line 20.

The flow controller apparatus 24 is conventional apparatus widely usedin the art and may be selected from amon the products of many instrumentmanufacturers. The use of air or other gas for the operation ofcontrollers and motor valves is very common and I will illustrate thiscontroller assembly as operating on air pressure.

The flow controller 24 may be set to be actuated at a certainpredetermined pressure differential of gas passing through the orifice2|. For normal operation this predetermined pressure differential mustbe somewhat higher than that corresponding to the rate at which gas isflashed from the liquid as the liquid enters the low pressure separatorI8. In operation, the flow controller 24 causes the motor valve I5 to beopen when the gas fiow through the orifice 2I is less than thatcorresponding to the setting of controller 24. The flow of gas throughthe orifice affects the controller by differences in pressure throughthe connecting tubes 22 and 23 positioned respectively upstream anddownstream of the orifice. As the motor valve I6 opens liquid flow fromthe high pressure separator I 2 to the low pressure separator I8increases and gas flow through the orifice 2| increases correspondingly.This increase affects the flow controller through the tubes 22 and 23and, when the increase is undesirably high, the

controller operates to close or to partly close the motor valve I6. Asthe level of the liquid in the separator I2 is lowered to the top 33 ofthe stand pipe I4, gas goes through the tube 3 I, through the venturiinto a line 36 and through line I5, valve I6, and pipe I'I into the lowpressure separator. The increased volume of gas in separator I8 thenpasses through the gas outlet line 28 and through the orifice 2| and theincreased pressure differential across this orifice causes the flowcontroller to operate and to partly close the motor valve I6. In thismanner, the greater the volume of gas passing from the high pressureseparator to the low pressure separator, the greater will be thetendency of the flow controller to close the motor valve and in thismanner the loss of high pressure gas will be reduced to a minimum.Referring to Figure 2, in normal operation the level or the liquid inthe high pressure separator is maintained between the top point 33 ofthe stand p p and the top side of the opening 31. Preferably, it remainsnearthe top 33. The bulk of the liquid enters the stand pipe through theinlet 3'! and a lesser amount of liquid enters through the opening 33when the liquid level is higher than the point 33. As the liquid levelfalls below point 33, gas is drawn through the inner tube 3| in anamount governed by the liquid level and the rate of liquid flow throughthe Venturi construction 34. {he maximum and minimum fluctuations inliquid level may be controlled by constructing the stand pipe as regardsthe position of the opening 3'! relative to the top 33 of the standpipe.

In starting the operation of this apparatus in systems in which theliquid rate may vary widely or where the amount of gas dissolved in theliquid is not known accurately, the gas flow through the orifice 2| maybe sufilciently high to allow a substantial amount of gas to escape fromthe separator I2 through the stand pipe I4 into the low pressureseparator I8. This high gas flow will allow for widely varying liquidrates without danger of liquid completely filling the separator I2. Asflow rates become more steady the setting of the controller 24 may belowered until it is only slightly higher than the amount of gas flashedin the low pressure separator, thus giving a normal operational control.The stand pipe I4 is designed by provision of tube SI so that as theliquid level is decreasing a small amount of gas will enter the standpipe before the liquid level is down to the main stand pipe opening 37.The amount of gas entering the stand pipe may be controlled according tothe diameter of the inner tube 3I. However, sufiicient gas should flowthrough the inner tube 3I when added to the gas flashed in the lowpressure separator that the total gas stream will be sufiiciently largeto operate the flow controller apparatus. A more steady flow of liquidmay ordinarily be obtained from the high pressure separator to the lowpressure separator when some gas enters the liquid stream through theinner tube 3| and in this manner hammering or knocking effects orrapidly closing off or opening up of valve I6 to liquid flow areavoided.

On laboratory or bench scale equipment for high pressure processes,regular types of liquid level controllers are diihcult and expensive toobtain. For example, in flow controllers for such small scale use, thefloats are so small that they have too little lifting power to actuatevalves or even pilots. Such control apparatus as the herein disclosedstand pipe may be made for small scale equipment by merely constructinga small stand pipe having an inner tube of small or even very smalldiameter and the side opening 31 may be of size sufiicient for passageof the volume of liquid being processed.

This level control apparatus as herein disclosed has special utility inhigh pressure separation steps, for example, in hydrogenation work inwhich liquid and gas may need be separated under such high pressures as5,000 pounds per square inch or even higher pressures. The materials ofconstruction need not be special materials, but should be selected fromthe point of view of resistance to corrosion of materials of theprocess. The high pressure separator tank, of course, and the motorvalve I6 should be of such design and construction as to functionproperly under the desired pressure. The motor valve I6 and the backpressure regulator 28 are the only moving pieces of equipment exposed tohigh pressures. Another advantage of my'invention is that in case repairor cleaning need be done to the auto "nates within the throat s maticcontrol apparatus such wcrk may be i done without depres'sur ing thehigh pressure-separator tank "Since "all Such equipment is Outside'oIthi's tank.

It will be obvious to those-skilled in "the art that For example, thetwo tubes3l and 32 need not be concentrically disposed, the inner *tube'"31 may be off center, as tubesll and-RS2 of Figure 3, with tube 41having a "terminal opening 4'3 as shown. And further, the 'tubetl neednot necessarily be disposed within tube -32,'as illustrated,but-it maybelpositioned'outside*th-e la'ttertubaas tube 4| of Figure '3. 'However,

the lower-end of the smaller through the sidewall of the venturi"structure may 'be tub'e'm'ust then'pass outer tube so that afrealiz'e'd. 'Th'eiupper end of the large tube may then be "closed "andthe openin "as shown. In

tub must carry "a "side still another form, the large diameter'tube'maybe shorter thanthe'sm'all diameter tube' and'its upper end terminatingwith afpipe L sothat the actual opening in the large diameter pipe will"e disposed'approximately in a vertical plane.

Having disclo'sedm'y invention, I claim:

1. An apparatus-for use in the -removal of gas and liquid from a, vesselcomprising an elongated vertically disposed tube of small diameter andopen at both ends, a second tube'of greater'diameter than the first tubeand disposedconcentric with and surrounding said first tube, the upperend of said first tube and the adjacent endof said second tube joined inagas-tight manner, the inner tube is of such length that :ittermiof --aventuri connected with the lower end of said second tube, and an openingin the sidewall ofthe second tube.

2. -An apparatus ior-use in the removal of gas andliquid irorna vesselcomprising an elongated vertically disposed tube of small diameter andopen at both ends, a second tube of greater diameter than the first tubesurrounding said first tube, the upper end jacent end of said secondtube joined in a gastight manner, the inner tube is of such length thatit terminates within the throat of a venturi connected with the lowerend of said outer tube, and an opening in the sidewall of the outertube.

3. An apparatus for use in and liquid from a vessel comprising a firstelongated and generally vertically disposed tube open at both ends, asecond tube rigidly attached to said first tube, one end of said secondtube is joined with one end of a venturi in such a manner that one endof said first tube terminates in the throat of the venturi, the otherend of said second tube terminating as an opening at a pointintermediate said venturi and the other end of said first tube, one axisof said terminal opening being horizontal,

4. In an apparatus for the separation of a gas from a liquid thecombination comprisin a first separator tank having an inlet pipe forintroduction of fiuid to be separated, an outlet pipe in the top of thetank for outlet of gas, an outlet pipe at the bottom for outlet ofliquid and gas, a motor valve disposed in said liquid and gas outletpipe, a second separator tank having an inlet of said first tube and thead pipeconnected with -said outlet "pipe of ssaid:ffirst "separator tankfor introduction of liquid and gas, an outlet pipe in the top ofsaidsecondseparator for outlet of gas and an outlet pipeatthe bottom"thereof for outlet of liquid, an elongated and vertically disposed:standpipe apparatus in the first separator tankcomprising, in combina'tion, a first elongated and vertically disposed tube,

a second elongated tube or greater diameter than said first tubedisposed concentric with andsurrounding said first tube, the top end ofsaid first tube joined with the'adjacent end of said second tubeto formagas-tight joint, the other end of said second tube joined with one endof a venturi in such a manner that the adjacent endof said first tubeterminatesin the throat ofthe venturi,

an opening in the wall or the second tube-at a midpoint between said.Ijoined end and said ven- "turi, the other end of the venturi "joinedwiththe inner end of said outlet pipe "at the bottom iof "said firsttank,saidstandpipe apparatus disposed in the lower "andliquid-containing portion ofsa'ijd z'first tank at 'sucha distance fromthe bottom-"of 'said first tank that said opening in the wall of saidzsec'ond tube is'positionecl at'a predetermined distance from thebottom'of the .tank at which it is desired to'maintain the lower levelof the'liquid, andmeans responsive to .thefiow of gasiin the'top outletpipe of said secondseparator tank for operatingsaid motor valveforremovinglliquiid and gas from said first separator .tank .iormaintenance of theliqriidilevel at'saidpredetermined distance from thebottom of .said first tank.

15. .In an apparatuslfor the separation of agas from ,a J liquid .thecombination comprising .a first separator tank having an inlet .pipe forintroduction of .fiuid to be. sep-arated,.an..outlet ,pipeiin theremoval of gas the top or the tank for outlet-of gas, an outlet ,pipe'atthe bottom ,for outlet of .liquidand .gas,.1a

.motor valve disposed in .sai'd liquidand .gasoutlet pipe; at secondseparatortankhaving an inletpipe connected with. saidoutlet pipe ofsaid. firstv separatortank :for. introduction of liquidand .gas,;-an

outlet; pipe in the top of said secondseparatorlfor outlet of gas and anoutlet pipe at-thebottom thereof for outlet of liquid, an elongated andvertically disposed standpipe apparatus in the first separator tankcomprising, in combination, a first elongated and vertically disposedtube, a second elongated tube surrounding said first tube, the top endof said first tube joined with the adjacent end of said second tube toform a gas-tight joint, the other end of said second tube joined withone end of a venturi in such a manner that the adjacent end of saidfirst tube terminates in the throat of the venturi, an opening in thewall of the outer tube, the other end of the venturi joined with theinner end of said outlet pipe at the bottom of said first tank, saidstandpipe apparatus disposed in the lower and liquid-containing portionof said first tank at such a distance from the bottom of said first tankthat the upper open end of said first tube is positioned at apredetermined distance from the bottom of the tank at which it isdesired to maintain the upper level of the liquid, and means responsiveto the flow of gas in the top outlet pipe of said second separator tankfor operating said motor valve for removing liquid and gas from saidfirst separator tank for maintenance of the liquid level at saidpredetermined distance from the bottom of said first tank.

6. In an apparatus for the separation of a gas from a liquid, thecombination comprising a first separator tank having an inlet pipe forintroduction of fluid to be separated, a gas outlet line disposed in thetop of the tank, a liquid and gas outlet line disposed in the bottomthereof, a liquid and gas withdrawal standpipe apparatus in the liquidcontaining portion of said first separating tank, said standpipeapparatus comprising, in combination, a first elongated and generallyvertically disposed tube open at both ends, a. second tube attached tosaid first tube, one end of said second tube being joined with one endof a venturi in such a manner that the lower end of said first tubeterminates in the throat of the venturi, the other end of said secondtube terminating as an opening at a point intermediate said venturi andthe other end of said first tube and said standpipe apparatus being sodis- .posed with respect to the bottom of said first separator tank thatsaid opening in the second tube defines the position of the lower levelof the liquid, a second separator tank having a gas outlet line in itstop, a liquid outlet line in its bottom and a side fluid inlet line,said liquid and gas outlet line from said first separator tank having amotor valve therein and communicating with said fluid inlet line of saidsecond separator, an orifice in the gas outlet line of said secondseparator tank and means responsive to the flow of gas through saidorifice to actuate said motor valve.

7. In an apparatus for the separation of a gas from a liquid, thecombination comprising a first separator tank having an inlet pipe forintroduction of fluid to be separated, a gas outlet line disposed in thetop of the tank, a liquid and gas outlet line disposed in the bottomthereof, a

liquid and gas withdrawal standpipe apparatus in the liquid containingportion of said first separating tank, said standpipe apparatuscomprising, in combination, a first elongated tube generally verticallydisposed and open at both ends, a generally vertically disposed secondtube joined at its lower end to one end of a venturi, said first tubebeing joined with said second tube in 'such a manner that the lower endof said first tube terminates in the throat of said venturi, an

opening in the second tube disposed above the venturi but below theupper end of said first tube, the other end of said venturi,communicating with the liquid and gas outlet line in the bottom of saidfirst tank and said standpipe apparatus being so disposed with respectto the bottom of said first separator tank that said opening in thesecond tube defines the position of the minimum level and the top end ofsaid first tube defines the position of the maximum level of the liquidin the tank, a second separator tank having a gas outlet line in itstop, a liquid outlet line in its bottom and a side fluid inlet line,said liquid and gas outlet line from said first separator tank having amotor valve therein and communicating with said fluid inlet line of saidsecond separator, an orifice in the gas outlet line of said secondseparator tank and means responsive to the flow of gas through saidorifice to actuate said motor valve.

8. An apparatus for the removal of gas and liquid from a vesselcomprising, in combination, a first elongated tube generally verticallydisposed and open at both ends, a generally vertically disposed secondtube joined at its lower end to one end of a venturi, said first tubebeing joined with said second tube in such a manner that the lower endof said first tube terminates in the throat of the venturi, and anopening in the second tube disposed at a point between said venturi andthe upper end of said first tube.

HENRY E. SHOBE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,841,505 Sweetland Jan. 19, 19322,225,949 Bennett Dec. 24, 1940 2,230,619 Katz Feb. 4, 1941 2,414,371Fragen et al. Jan. 14, 1947 FOREIGN PATENTS Number Country Date 546,130Great Britain June 29, 1943

1. AN APPARATUS FOR USE IN THE REMOVAL OF GAS AND LIQUID FROM A VESSELCOMPRISING AN ELONGATED VERTICALLY DISPOSED TUBE OF SMALL DIAMETER ANDOPEN AT BOTH ENDS, A SECOND TUBE OF GREATER DIAMETER THAN THE FIRST TUBEAND DISPOSED CONCENTRIC WITH AND SURROUNDING SAID FIRST TUBE, THE UPPEREND OF SAID FIRST TUBE AND THE ADJACENT END OF SAID SECOND TUBE JOINEDIN A GAS-TIGHT MANNER, THE INNER TUBE IS OF SUCH LENGTH THAT ITTERMINATES WITHIN THE THROAT OF A VENTURI CONNECTED WITH THELOWER END OFSAID SECOND TUBE, AND AN OPENING IN THE SIDEWALL OF SAID SECOND TUBE.